Japanese patent laid open publication (kokai) No. 2004-322822 discloses a rear vehicle body structure suitable for a hatchback passenger vehicle that has no rear bulkhead for separating a rear luggage compartment from a passenger compartment. Each rear floor frame of this rear vehicle body structure comprises a kickup portion that is bent upward from a rear end of the rear floor frame and extends horizontally and a reinforcement that extends horizontally below the kickup portion in a parallel relationship, and the rear ends of these frame members are connected to a rear pillar. A suspension support member extends in a fore-and-aft direction of the vehicle body between the rear pillar and a quarter pillar provided immediately behind the rear seat.
According to this arrangement, the rigidity of the rear part of the vehicle body is increased, and the vehicle body is made more resistant to a rear end collision. However, the distribution of the load of a rear end collision is not necessarily optimally distributed depending on the mode of the rear end collision, and there is no effective measure against a rear end crash by a taller vehicle.
Japanese patent laid open publication (kokai) No. 2006-273134 discloses a rear vehicle body structure in which an arcuate frame member joins each longitudinally extending rear floor side member with a rear cross member extending laterally across the vehicle body at a higher elevation than the rear floor side member.
This provides a measure against a rear end crash by a taller vehicle and promotes a favorable distribution of a load of a rear end crash, but these effects are not entirely satisfactory. Furthermore, this arrangement requires some space between the rear seat and rear cross member which a small hatchback passenger vehicle cannot afford.